North American Network Operators Group
Date Prev | Date Next | Date Index | Thread Index | Author Index | Historical

Re: Getting a "portable" /19 or /20

  • From: Sean M. Doran
  • Date: Wed Apr 11 00:42:15 2001 
Greg Maxwell <[email protected]> writes:

| > 	Aggregation buys time, that's it.  Aggregation does not make the
| > current routing methods any more scalable.
|
| In IPv4 yes, because you can't have perfect aggregation, too much network
| multihoming and old prefixes and it's to painful to change address blocks.
|
| In IPv6, if implimented right aggregation provides for virtually limitless
| scalability for unicast traffic.

Perfectly aggregated networks are star-shaped.  

Any more complicated topology cannot be perfectly aggregated.

In real networks, aggregation at best follows a "reasonable"
trade-off between optimizing and stabilizing route selection.
Not everyone will agree on what is a "reasonable" balance.  

Result: some people unhappy about suboptimal routing ("my packets
to my neighbour across the street go through another country") and
some people unhappy about too-great dynamicism ("damn, time to upgrade
to a faster processor, more memory, faster memory, etc etc etc").

This is a result of the CIDR addressing architecture and is 
INDEPENDENT OF THE NUMBER OF BITS IN AN ADDRESS.

	Sean.